Traditionally, minicomputers have been used for the collection and analysis of data generated by flow cytometers. One reason is that, until recently, microcomputers, which would be more cost-effective alternatives, were not sufficiently developed to satisfy the unique demands imposed by flow cytometers. In order to overcome some of the deficiencies of early generations of microcomputers, several of the functions required for data collection, such as analog to digital conversion and data storage in static RAM have been performed "external" to the computer which was used for the data analysis. In addition, "mixed" flow cytometry systems in which data are collected with a minicomputer and analyzed with a microcomputer have been developed. However, these approaches are not cost effective and do not effectively use the improved capabilities of available microcomputers. With the evolution of the Intel 80XXX family of processors, reliable peripherals, and a variety of powerful compilers, it has become feasible to develop a relatively inexpensive microcomputer-based data collection and analysis system for flow cytometry that performs as well as, or better than, minicomputer-based systems. The key link between the flow cytometer and the microcomputer is the electronic interface system that collects, processes, and conditions the analog signals from the preamplifiers of the four detectors. We have developed such a system, effectively solving the problem of interfacing asynchronous and synchronous data conversion, acquisition and storage. The interface system operates in a "handshake" fashion with the microcomputer. After initialization or the completion of data storage by the microcomputer, the interface module resumes control from the microcomputer, resets itself to clear the previous reading, and waits for the passage of the next cell through the flow cytometer. When a cell is detected, the interface module integrates the four analog signals for 20-35 microseconds, hold the value, and sends a "data ready" signal to the microcomputer, which then resumes control, reads the four integrated values, stores them in RAM, updates the real-time data display, and returns control to the interface module. The performance of the system has validated using microcomputers. With standardized beads, we obtained histograms with CV's (coefficients of variation) of 1.6%.